1. Field of the Invention
The present invention relates to a method of producing a bromine compound by brominating a compound having an aliphatic unsaturated bond. More specifically, it relates to a method of producing a high-purity bromine compound from a compound having an aliphatic unsaturated bond industrially advantageously.
2. Prior Art
Generally speaking, the bromination reaction of an aliphatic unsaturated group is frequently used for the synthesis of brominated derivatives in the field of organic chemistry. However, reaction heat must be removed from a reaction system because heat generated by the reaction is strong. Therefore, the operation of adding bromine little by little in a mild condition by cooling the reaction system is generally employed.
For instance. JP-B 49-39655 (the term "JP-B" as used herein means an "examined Japanese patent publication") discloses a method of producing .beta.,.gamma.-dibromopropylbenzene and teaches that a reaction is carried out at a low temperature at which a secondary reaction does not occur when bromine is added.
JP-A 55-111429 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses that a diallyl ether obtained from 2,2-bis{(4-hydroxy-3,5-dibromo)phenyl}propane and allyl chloride is brominated in a halogenated aromatic hydrocarbon as solvent, teaches that this bromination is carried out at a temperature of 10 to 30.degree. C., particularly 15 to 25.degree. C. and specifies in Examples that bromine is added at a temperature of about 20.degree. C. under cooling.
JP-A 50-30853 discloses a solid recovery method and teaches that bromine is added dropwise at a temperature of 20.degree. C. or lower to carry out a reaction between the bromine and 2,2-bis{(3,5-dibromo-4-allyloxy)phenyl}propane in Examples.
JP-A 7-173092 teaches that bromine is added dropwise at a reaction temperature of 10 to 20.degree. C. in 1 hour to carry out a reaction between the bromine and 2,2-bis{(3,5-dibromo-4-allyloxy)phenyl}propane so as to obtain a 2,3-dibromopropyl compound.
Further, JP-A 7-316087 discloses as an example that bromine is added dropwise to a methylene chloride solution of 2,2-bis{(3,5-dibromo-4-allyloxy)phenyl}propane in 1 hour while the reaction temperature is controlled to 24 to 27.degree. C. by using a cooling pipe.
Meanwhile, JP-B 50-23693, for example, disclose as an example that bromine is reacted with bis{(3,5-dibromo-4-allyloxy)phenyl}sulfone at the boiling point of methylene chloride by dissolving the compound in methylene chloride in the bromination of bis{(3,5-dibromo-4-allyloxy)phenyl}sulfone.
JP-A 3-271267 and JP-A 4-234354 disclose the bromination of bis{(3,5-dibromo-4-allyloxy)phenyl}sulfone and teach that bromine is added to a methylene chloride solution of the above compound at 39.degree. C. or 40.degree. C. in 1 hour and at 35 to 39.degree. C. in 1.5 hours, respectively. In these methods, the reaction is carried out in a reactor having a cooling pipe.
In all of the methods disclosed by these publications, the reaction is a small-scale laboratory-level reaction, a flask is frequently used as a reactor, and reaction heat is removed by cooling the reactor itself in most cases. These publications disclose conditions and means for carrying out the laboratory level reaction but not concrete conditions and means for removing a large amount of generated reaction heat effectively and for obtaining a high-purity bromine compound at a high yield on an industrial scale.
To carry out the bromination of a compound having an aliphatic unsaturated bond, particularly to carry out the introduction of many bromine atoms on an industrial scale, a large amount of generated reaction heat must be removed effectively. The development of means and an apparatus for this is desired. When reaction heat is not removed effectively, bromine must be supplied little by little and hence, the reaction time is prolonged, resulting in lowered yield and purity.